Molding machinery

ABSTRACT

MACHINERY FOR MOLDING ARTICLES INCLUDING A DEVICE FOR METERING, MIXING AND DISPENSING A MEASURED QUANTITY OF MULTIPLE COMPONENT MIXTURE TO A PLURALITY OF MOLDS. THE DISPENSING APPARATUS AND MOLDS ARE PROVIDED WITH COOPERATIVE ELEMENTS EFFECTIVE WHEREBY THE SPRUE PASSAGE OF THE DISPENSING DEVICE IS AUTOMATICALLY SELF-CLEANING AFTER EACH SHOT OF MATERIAL.

June 13, 1972 G. F. MCLEAN, JR

MOLDING MACHINERY '7 Sheets-Sheet 2 Filed Oct. 6, 1969 Wm H June 13,1972 G. F. McLEAN, JR 3,669,600

MOLDING MACHINERY Filed Oct. 6, 1969 '7 Sheets-Sheet 5 June 13, 1972 e.F. McLEAN, JR

MOLDING mcnmmmr 7 Sheets-Sheet 5 Filed Oct. 6, 1969 ZZZ June 13, 1972 G.F. MOLEAN, JR

MOLDING MACHINERY '7 Sheets-Sheec 6 Filed 001.. 6, 1969 June 13, 1972 G.F. MGLEAN, JR

MOLDING MACHINERY '7 Sheets-Sheet 7 Filed Oct. 6, 1969 3,669 600 MOLDINGMACHINERY George F. McLean, Jr., Middleton, Mass, assignor to USMCorporation, Flemington, NJ. Filed Oct. 6, 1969, Ser. No. 863,820

' Int. Cl. B291? 1/03 US. Cl. 425245 2 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND. OF THE INVENTION This invention relates to a machine formolding plastics material including mixing and dispensing apparatus andmore particularly to an arrangement for dispensing multiple componentmixtures, such as polyurethane or other like materials to a plurality ofmolds as well as-the molds employed therein.

Heretofore various devices have been presented for mixing multicomponentformulations, many of which are adaptable 'for the preparation ofurethane materials for use in a molding process. One such device isdescribed in US. Pat. No. 3,386,623, issued June 4, 1968 and assigned tothe assignee of the present invention. This device provides a mixingchamber for receiving reactants, a high speed agitator at one end of thechamber for mixing the reactants, ports for admitting the reactants intothe chamber and a discharge nozzle located at the same end of thechamber for dispensing the mixture. The constituent materials aremeasured into the mixing chamber in sequence, after which they aredischarged through the nozzle to a mold assembly.

In the use of the above mentioned device, as well as the mixing anddispensing device disclosed herein with a plurality of mold stations, aneed has arisen to insure that the sprue passage in the dispensingdevice remain free of molding material between shots. In operation ofthe dispensing device with polyurethane or like materials, should aportion of material from a previous dispensing operation remain in thesprue passage, the next shot of material containing this residue wouldin most instances produce an inferior product. Further, in the eventthat a material were to completely set up in the sprue passage, it wouldrequire shutting down the device to clean the sprue passage priortodelivering the next shot of material to a mold.

It is therefore an object of the invention toprovide molding machinerywherein the flow path from the mixer to the mold is self-cleaning aftereach shot of material is completed.

SUMMARY OF THE INVENTION for mixing the components contained therein andmeans for dispensing the components, after mixing, into a mold,

assembly.

The dispensing apparatus is efiective to cooperate with- Patented June13, 1972 a mold assembly to completely remove all volume from the flowpath of thesprue nozzle, when a shot of material has been deposited intothe mold. After completion of a shot of material into a mold, means isprovided for closing the mixing chamber and forcing substantially all ofthe material from the sprue opening into the mold; Means is furtherprovided on the mold, andoperated by the dispensing apparatus, to wipethe face of the sprue opening and to close the mold, such means beingeifective to substantially remove all material from the sprue opening,after each shot of material is completed;

BRIEF DESCRIPTION OF THE DRAWINGS The novel features that are consideredcharacteristic of the invention are set forth in the appended claims;the invention itself however,-both as to its organization and method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of a specificembodiment when rerad tin conjunction with the accompanying drawings, in'w 10 z FIG. 1 is a plan view showing one form ofmolding apparatushousing the present invention embodied therein;

FIG. 2 is an elevational view partly in section showing a portion of theapparatus of FIG. 1 taken on an'e'nlarged scale for clarity;

FIG. 3 is a sectional plan view taken along the line III-III of FIG. 2,showing details of the structure of FIGS. 1 and 2 taken on an enlargedscale;

FIG. 4 is a sectional view taken along the lines IV-IV of FIG. 2 showingfurther details of the structure;

FIG. 5 is an elevational view partly inv section taken along lines VV ofFIG. 3;

FIG. 6 is an elevational view showing a portion of the structure of FIG,2 taken on a greatly enlarged scale;

FIGS. 7 through 9 are sectional views taken alo'n'gthe lines VII-VII ofFIG. 6 showing the elements during operation of the device of FIG. 6;

FIG. 10 is an elevational sectional viewtaken substantially along theline X-X of FIG. 6 and showing further details of that structure; and

FIG. 11 is a sectional view similar to FIGS. 7 through 10 showing theoperative elements of the machine pre pared for mating prior toinjecting material into the mold.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingsand particularly FIGS. 1 and 2 there is shown a molding apparatus 10comprising a mixer assembly 12 and supporting frame work 14. The framework 1 4 comprises a plurality of mold receiving stations 11 arcuatelyarranged and located about the periphery thereof. Each of themoldstations 11 is provided with means for receiving and retaining a moldassembly 16. The frame work 14' also comprises a housing 18 dispos'ed'substantially at the center of the mold stations 11, and having aplurality of radialmemb'ers 20 extending outwardly therefrom.

A continuous track 22' is disposed adjacent the mold stations 11. Theradial members 20 thus provide. support for the track 22 and for'aplurality of sprockets 24 having a. chain 26 passing over them. Thechain 26 is continuous and extends over the sprockets 24', a sprocket 28mounted on' the frame work 14, and over a pair of idler sprockets 29'-and' 30" to a drive sprocket32'.

- Referring now, particularly to FIG. 2 it will be observed that thehousing 18 is' mounted on a stationary shaft 34, for rotational movementabout the shaft. A mixer support frame having a pair of side members 36and 38 and a cross brace 40 is attached to the housing 18, and extendingforwardly from the cross brace 40are a pair of slide provided to supportthe outermost end of the mixer sup" port structure, the wheels. beingreceived in the track 22. A boss 56 extends downwardly from the mixerhousing 46 and is attached to the chain 26. Thus. when the chain 26 ismoved by the drive sprocket 32, the mixer housing 46 is caused tomove'from one station to another, and

t the double acting cylinder 48, when actuated, is effective to move thehousing 46 toward and away from a mold assembly 16. 1

Referring now to FIGS. 1 and 2, taken in connectio with FIG. 5, themixer housing 46 will be seen to have a pair of bearing housings 58 and60 for receiving a shaft 62. On one endof the shaft 62 is affixed a dialmember 64 having threaded openings for receiving a plurality ofadjustable elements in the form of hex head bolts 66. The opposite endof the shaft 62 is attached through a universal joint 68 to a splineshaft 70. A bearing assembly is mounted in a housing 72 and receives ashaft 74 with internal splines for receiving the shaft 70. The shaft 74is captive in the housing 72 and has at one end a beveled gear 76 inmating relation witha beveled gear 78 affixed to the stationary shaft34.

From the foregoing, it may be observed that rotation of the housing 46about the stationary shaft 34 causes rotation of the dial member 64, andby means of the spline shaft 70, movement of the housing 46 toward andawa from the shaft 34 may be accomplished without effecting rotation ofthe dial 64.

It should here be explained that the number of adjustable elements 66and their location on the dial 64 is generally arranged such that withthe arrival of the mixer assembly at each station, a different element66 is located adjacent a roller 80 disposed on the mixer assembly. Whilea more lengthy description of the operation of the mixer assembly 12will be offered as the description proceeds, it will be sufficient hereto say that the location of the roller 80 with respect to the dial 64 iseffective to control the volume of material to be dispensed from themixer assembly 12. Thus, by marking the dial member 64 with suitableindicia to correspond to the mold station 11 at which the respectiveelements 66 will contact the roller 80, the bolts may be adjusted bythreadedly turning them into the dial 64 or backing them from the dial,to provide a length to control the quantity of material dispensed tothat quantity required by a given mold at the respective mold ,stations.

Referring now to FIGS. 2 through 5, the mixer housing 46 has attachedthereto a bracket 82 which supports an hydraulically dampened cylinder84 in which there is located a movable piston connected to one end of apiston rod 86. The opposite end of the rod 86 is affixed to a mixing.chamber piston 88 which slidingly engages the inside wall of a mixingchamber 90 to form a chamber expandable through movement of the piston88 therein.

The piston 88 maybe of a rubber-like material for'affording a close fitwith the wall of the chamber 90. The rod 86 is further provided with aswitch actuator flange 92 which is engageable with an injection stopswitch S connected to the housing 46 by means of a bracket 94.

The cylinder 84 is further provided with, an air line 96 which isconnected to a source of air under pressure (not shown), effective tocause movement of the piston in the cylinder 84 when applied to thecylinder, with a resultant movement of the mixing chamber piston 88 andthe flange 92. ,The movement of the piston 88 in. the downward directionis thereby effective to cause substantial emptying of the mixture in themixing chamber 90, as will be further described hereinbelow.

A block 98 having a recess forming the bottom portion i of the. mixingchamber is mounted on the" housing 46 and retains mixing chamber inletvalve means for components A and B which are supplied to the mixer'fro'mstorage tanks (not shown), and also mixing chamber agitator means.

The block 98 is further provided with a bore 100 for retaining themixing chamber agitating means. The bore 100 receives a bearing in whichis mounted a shaft 102 rotatable at high speed by an electric motor 104held by a bracket to the underside of the housing 46. The end of theshaft 102 remote from the motor 104 is provided with a mixing member 106disposed in an enlarged portion of the bore 100.

The block 98 has a pair of cylindrical bores 108 and 110 formed thereinwhich receive inlet fittings which in turn receive a pair of component A& B discharge lines 112 and 114 respectively.

The block 98 is provided with still another cylindrical bore 116 (FIG.10) which is connected to the injection nozzle of the machine throughwhich mix is dispensed during an injection'operation.

Adjacent to the lower portion of the block 98, and connecting into bores108 and 110 respectively are a pair of valve means V1 and V2 which serveto control the flow of component A and component B material into themixing chamber 90. The valve V1 comprises a plunger element 118 whichoperates through a diaphragmarrangement and extends into a bore whichintersects with the bore 108 and opens into the chamber 90. In likemanner the valve V2 is provided with anplunger 120 which operatesthrough a diaphragm andextends upwardly into a bore opening into themixing chamber 90 and intersecting the bore 110. Each of the valves V1and V2 areoperatively connected to pneumatic cylinders which serve tooperate the plungers 118 and 120. The pneumatic cylinders are connectedinto a control circuit which sequence of operation will be explained ingreater detail as the description proceeds. 6

Referring particularly to FIG. 3 taken in connection with FIGS. 2, 4 and5 it will be observed that the block 98 further serves to support theconstituent material metering means, which is effective to provide,material to the mixing chamber 90. A pair of pneumatically ac.-

tuated cylinders 122 and 124 are pivotally attached to the housing 46and have a pair of piston rods 126 and 128 respectively extendingdownwardly therefrom. v

A pair of cylindrical chambers 130 and 132 which may be of differentdiameters, and of expandable volume by virtue of freely movable pistons134 and 136 disposed therein, are mounted on the block 98 substantiallyin alignment with the rods 126 and 128. A pair of piston rods 138, 140having one end operati-vely connected to the pistons 134 and 136respectively, have their opposite ends connected to the rods 126 and 128respectively such that through operation of they pneumatic'cylinders 122and 124, the pistons 134 and 136 are moved to change the volume of thecylindrical chambers 130 and 132. It should also be understood that withthe cylinders 122 and 124 ,unpressurized, fluid entering the chambers130 and 132 is effective to cause movement of the pistons l34'and 136thus changing the volume of the chambers. Near the bottom end of thechambers 130 and 132, a pair of valve members V3 and V4 are mounted inthe block 98 to control the entry of material into the respectivechambers from the lines 1 10 and 112. A pneumatic cylinder provides formovement of a valve stem in val-ve V3 which is effective to openor'close the inlet to the bore 108 and a side bore 142 leading tothechamber 130. In like manner, the line 112 leading into the bore 140and subsequently to a side bore 144 is opened or closed by the valve V4.Each of the'cylindrical chambers 130 and 132 is thereby connected in aclosed fluid flow path leading from the storage tanks which supply thecomponent A and component B,

The means for metering the components A and B is generally controlled bythe ratioing system as supported by the housing 46 and shown in detailin FIGS. 2, 3 and 4. The housing 46 is provided with a pair of bosses146, 148 to which a sine bar member 150 is connected by a shaft '152.Near the end of the sine bar 150 at which the roller 80 is disposed,there is pivotally mounted a pneumatic cylinder 154 which has one endpivotally attached to the housing 46. As best shown in FIG. 2, thecylinder 154 is effective in its operation to move the sine bar 1150about the pivot shaft 152 to a position out of contact with the dial 64,when the dial is being rotated.

Referring now particularly to FIGS. 3 and 4, it will be seen that thehousing 46 is provided with a pair of parallel rods 156 and 158 disposedadjacent one side thereof, and a second pair of parallel rods 160 and162 disposed adjacent the opposite side of the housing. A switch supportmember 164 having a pair of switches S6 and S7 mounted thereon isslidably mounted on the rods 156 and 158, the switches being aligned forcontact with a flange 166 mounted on the piston rod 126. Another switchS8 is mounted for adjustable movement along the rod 156 and is alignedfor contact by an arm 168 extending from the piston rod 128. It willalso be noted that with the piston rod 128 in its fully retractedposition, the arm 168 is effective to contact a switch S2 aflixed to thehousing 46.

At the opposite side of the housing 46, a switch support member i170 isslidably mounted on the rod 162 and has the switches S4 and S5 mountedthereon. A slide block 172 is slidably mounted on the rod 160 and isconnected to the support member 170 by a pair of parallel rods 174 and176 to form a unitary slidable structure. The piston rod 126 is providedwith a flange 178 aligned for contact with the switches S4 and S5, andan arm 180 extends outwardly from the rod to contact a switch S3 mountedon the housing 46, when the piston 122 is in its fully retractedposition.

As will be fully appreciated from observing FIGS. 3 and 4, the novelratio system and volume control is characterized by the sine bar 150which is effective to provide a preselected volume of the material in aconstant ratio which is selected by location of the switches S4, S5, S6,and S7. To this end, the sine bar 150 is provided with a slot 182 on oneside thereof, and a slot 184 on the opposite side. The slot 182 receivesa roller 186 attached to a flanged portion of the switch support member:164. The slot 184 receives a roller i188 mounted on a movable block190. The block 190 is threadedly received on a rod 192 supported betweenthe slide block 172 and the switch support member 170. A knurled knob 194 is provided at the end of the rod 192 and by rotating the knob, theblock 190 is moved along the rod 192. Thus, by moving the block 190along the rod 192, the relationship between the location of the switchesS4, S5, and switches S6, and S7 is changed to change the ratio ofmaterials to be mixed in the mixing chamber.

Referring now to FIGS. 6 through 11 there is shown a novel apparatus forremoving material from the sprue of the dispensing apparatus betweenshots of material provided to a mold. As shown in FIG. 6, the face ofthe block '98 is provided with a bracket 200 from which a cylinder 202is pivotally suspended. The cylinder 202 is of a double acting type andprovided with fluid pressure from a pressure source (not shown), Apiston rod 204 extends from the cylinder 202 and is connected to a block206 which straddles a lever arm 208.

As best shown in FIGS. 6 and 7 the face of the block 98 is cut out toform a recessed portion 210, and the lever arm 208 is pivotallysupported by a pin 212 for movement within the recess 210. A bracket 214is attached to the cylinder 202 and has mounted thereon a microswitchS12 in alignment for activation by contacting an L shaped flange 216extending upwardly from the lever arm 208. The lever arm 208 is thusrotatable by pressurizing the cylinder 202 which causes the lever arm topivot about the pin 212, the flange 216 contacting the microswitch S12and a pair of downwardly extending fingers 218 and 220 serving tooperate on a mating mold assembly 16.

As will be observed particularly in FIGS. 7 and 10 a sprue channel 222is provided in the block 98, terminating in a sprue outlet 224 at theface of the block. The outlet bore 116 leading from the chamber entersinto the sprue channel 222 and a valve rod 226 is movable in the channelto open and close the bore 116. The valve rod 226 is actuated by a fluidoperated cylinder (not shown) and travels from the position shown inFIG. 10 to the position shown in FIG. 11, where the end of the valve rodis flush with the face surface of the sprue outlet 224.

Referring now to FIGS. 7 through 10 the mold assembly is provided with asprue 228 leading from a mold chamber 230 and disposed substantially atthe mold part line. The mold sprue 228 extends from the mold properthrough a bearing block 232 in which a shutter member 234 is slidablyretained. The shutter member 234 has a tapered edge 236 which slidesacross the inlet of the mold sprue 228 to substantially close the spruewhen in the position shown in FIG. 9.

A roller 238 is attached to one end of the shutter member 234 andextends from the mold assembly 16 such that when the outer surface ofthe shutter 234 is in mating engagement with the face of the sprueoutlet 224 the roller is disposed between the fingers 218 and 220 of thelever arm 208.

In operation, the dispensing apparatus is brought up to mate with themold assembly 16, as in FIG. 11 which shows the block 98 and the moldassembly 16 just prior to contact. The valve rod 226 is retracted to theposition shown in FIG, 10 and material flows into the mold chamber 230through the sprue channel 222 and the mold sprue 228. On completion ofthe injection operation, the control circuit sends a signal to theactuator for the valve rod 226 and the rod is moved forward to close offthe bore 116 and force the material from the sprue 222 into the mold,the rod 226 terminating its travel at a position as shown in FIG. 8. Thecircuitry then actuates the cylinder 202 which rotates the lever arm tothe dot dash position shown in FIG. 6 which moves the shutter 234 to theposition shown in FIG. 9.

As will be observed, the shutter member 234 serves to close off the moldsprue 228 and additionally completely wipes the face surface of thesprue outlet 224 as well as the valve rod 226 of any material leftthereon. By virtue of the tapered surface of the edge 236, the materialwiped from the elements is forced into the mold cavity 230.

The cylinder 202 is then actuated to bring the lever arm back to theposition shown in FIG. 6, however, the fingers 218 and 220 are so spacedthat the movement does not reopen the shutter member 234. The dispensingapparatus may now be moved to the next mold assembly, the entire spruechannel 222 and surface adjacent the outlet 224 being free of anymaterial from the previous shot.

In a typical sequence of operation, a plurality of mold assemblies 16are arranged at the mold assembly stations 11 in an acuate fashion. Themixer assembly 12 is in its rearwardmost position, adjacent to thehousing 18 and in alignment with a mold Station. With the valves V1 andV2 in the closed position, the cylinder 154 is activated to bring theroller 80 in contact with an element 66 which has been set to reflectthe volume of the aligned mold assembly 16. The sine bar is now locatedsuch that the switches S4, S5, and S6, S7 are disposed in the propervolume location to meet the needs of a mold assembly 16 mounted at theStation 11 where the mixer assembly 12 is disposed. On a signal from thecircuit the cylinder 48 moves the mixer assembly 12 toward the moldassembly 16 and engagement takes place between the two assemblies. Withthe valves V3 and V4 closed, valve V2 is opened and the cylinder 124activated to force the piston 136 downward into the cylinder and thecomponent material contained therein into the mixing chamber 90. ValveV2 is then closed and valve V1 opened to provide a shot of reactantmaterial from the chamber 130 into the mixing chamber'90 in a similarmanner, the valve V1 being closed on completion of the metering step.

In metering the proper quantities of material to the mixing chamber 90,piston 136 moves downwardly until the flange 166 contacts first theswitch S7 to retard motion of the piston and then the switch S6 whichstops motion of the piston. In like manner, the piston 134 movesdownward until the flange 178 contacts first the switch S5 and then theswitch S4 to meter the proper quantity of material from the chamber 130to the mixing chamber 90.

It will be noted that at this time the cylinder 84 is unpressurized andvented such that entry of fluid into the chamber 90 causes the piston 88to rise in response to the entering fluid.

In providing machinery which is both eflicient and effective inoperation, the circuitry of the present machinery is set up such thatwhile the piston 134 is being moved to provide material to the mixingchamber 90 via valve V4 is opened and material is forced from thestorage tanks into the chamber 132 to refill the chamber. In refilling,the piston 136 is caused to move in the chamber 132 by the fluidentering the chamber until the arm 168 contacts the switch 82 which iseffective to close the valve V4 and stop the flow of material into theline 112.

Upon completion of the metering of material into the chamber 90, valveV3 is opened and a new charge of material is forced from the storagetank of reactant material into the chamber 130. The piston 134 is causedto move by fluid entering the chamber 130, until the arm 180 contactsthe switch 53 which is eflective to close the valve V3 and stop the flowof material from the tank.

With the chamber 90 now containing a proper quantity of material themixing member 106 is rotated by the motor 104 and the material is mixed.

After a suitable time delay in the circuitry, the valve rod 226 isretracted to the position shown in FIG. and the piston 88 is moveddownwardly by action of the cylinder 84 until contact is made withswitch S10 signaling the circuit that the entire shot of material hasbeen sent to the mold assembly 16.

In sequence, on signal from the switch S10, the valve rod 226 is movedto its forwardmost position as shown in FIGS. 8 and 9, and the piston202 is activated to cause the shutter member 234 to move to the closedposition as shown in FIG. 9. The cylinder 202 is again activated to movethe lever arm 208 to the position shown in FIG. 6 and contact with theswitch S12 signals the circuit that the next sequence of operation is totake place.

It should here be noted that contact of the switch S10 which signals thecircuit that the material has been evacuated from the mixing chamber isalso effective to open the valve V2 and activate the cylinder 124 tosend a charge of material from the chamber 132 into the mixing chamber90 to prevent further reaction of the constituent materials in thechamber. The purge charge sent into the mixing chamber 90 is determinedby the location of the switch S8 on the rod 158, which is adjustable.Thus, the piston 136 moves downwardly until the arm 168 contacts theswitch S8 and a partial charge of material now remains in the chamberwhich is diluted by the material from chamber 132 to the extent thatsubstantially no reaction takes place.

With the purge shot located in the mixing chamber 90 and the face of thesprue outlet 224 as well as the sprue passage 226 substantially devoidof material by virtue of the action of the shutter member 234 and thevalve rod 8 226, cylinder 148 is activated to move the mixer assembly 12back toward the housing 18 and the piston 154 is activated to move thesine bar 150 to contact the switch S1. The switch S1 signals the circuitthat the sine bar 150 is out of contact with the dial 64 and theapparatus is ready to be moved to the next station.

The drive wheel 32 is now rotated by power means (not shown) and themixer assembly 12 is caused to move to the next station. As will beevident from FIG. 2, movement of the mixer assembly 12 causes rotationof the dial 64 and a new volume controlling element 66 is moved to aposition in alignment with the roller 80.

Thus located, the sequence of operation as hereinbefore set forth isrepeated to provide material to a mold assembly 16 located at the newstation 11.

It might be well to herein note, that by rotating the knob 194 andthereby adjustably locating the switches S5, S4 in relation to theswitches S6 and S7 a new ratio of component material to reactantmaterial may be set up. The ratio thus set up, will not vary as thevolume is changed through operation of the sine bar 150, in that thegeometrical arrangement of the switches 54, 55 and 56, 57 is such thatmovement of the sine bar about the axis 152 is effective to cause changein volume only without changing the ratio of the constituent material tothe reactant material.

In addition, while the various switches that have been mentioned are notshown in a complete circuit, it is considered that it is well within thestate of the electrical art to provide a suitable circuit in which theswitches as hereinbefore set forth will function in the proper sequenceas described.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. Molding apparatus comprising the combination of a dispensing devicefor supplying liquid material and having a sprue passage through whichthe material is fed to a sprue opening, a mold assembly for receivingmaterial from said device having a mold cavity and a sprue entering intosaid cavity and terminating adjacent said dispensing device sprueopening, and a slidable member disposed on said mold assembly forclosing said mold sprue and simultaneously wiping said sprue opening ofsaid dispensing device, said member having one surface arranged forclose fitting engagement with a surface of said mold assembly adjacentsaid mold sprue, an opposite surface arranged for close fittingengagement with a surface of said dispensing device adjacent saiddispensing device sprue opening, and a leading edge surface taperedrearwardly and toward said mold sprue for substantially forcing materialinto said mold sprue during a sprue closing operation.

2. Molding apparatus as set forth in claim 1 which further includesmeans on said dispensing device for moving said slidable member to closesaid mold sprue.

References Cited UNITED STATES PATENTS 1,101,053 6/1914 Bland 18-30WD2,43 6,122 2/ 1948 Rotsler 18DIG 51 2,585,204 2/ 1952 Wondra 18-30 NY2,992,455 7/ 1961 Salzman 18-DIG 51 3,172,161 3/ 1965 Trueblood 1830 NWJ. SPENCER OVERHOLSER, Primary Examiner N. E. LEHRER, Assistant ExaminerUS. Cl. X.R. 42520O

